Numerical Investigation of the Flutter of a Spherical Shell

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Mohamed Menaa ◽  
Aouni A. Lakis
Keyword(s):  
Finite Element ◽  
Spherical Shell ◽  
High Speed ◽  
Structural Model ◽  
Correction Term ◽  
Theoretical Data ◽  
Element Formulation ◽  
Spherical Shells ◽  
Flow Parameters ◽  
Nodal Displacements

In this study, aeroelastic analysis of a spherical shell subjected to external supersonic airflow is carried out. The structural model is based on a combination of the linear spherical shell theory and the classic finite element method (FEM). In this hybrid method, the nodal displacements are found from the exact solution of shell governing equations rather than approximated by polynomial functions. Therefore, the number of elements chosen is a function of the complexity of the structure. Convergence is rapid. It is not necessary to choose a large number of elements to obtain good results. Linearized first-order potential (piston) theory with the curvature correction term is coupled with the structural model to account for pressure loading. The linear mass, stiffness, and damping matrices are found using the hybrid finite element formulation. Aeroelastic equations are numerically derived and solved. The results are validated using the numerical and theoretical data available in literature. The analysis is accomplished for spherical shells with different boundary conditions, geometries, flow parameters, and radius to thickness ratios. the results show that the spherical shell loses its stability through coupled-mode flutter. This proposed hybrid FEM can be used efficiently for the design and analysis of spherical shells employed in high speed aircraft structures.

Free Vibration of Spherical Shells Using a Hybrid Finite Element Method

2015 ◽  
Vol 15 (04) ◽  
pp. 1450062 ◽  
Author(s):  
Mohamed Menaa ◽  
Aouni A. Lakis
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Free Vibration ◽  
Theoretical Data ◽  
Free Vibration Analysis ◽  
Element Formulation ◽  
Spherical Shells ◽  
Hybrid Finite Element Method ◽  
Hybrid Finite Element ◽  
Element Method

In this study, free vibration analysis of spherical shell is carried out. The structural model is based on a combination of thin shell theory and the classical finite element method. Free vibration equations using the hybrid finite element formulation are derived and solved numerically. Therefore, the number of elements chosen is function of the complexity of the structure. Convergence is rapid. It is not necessary to choose a large number of elements to obtain good results. The results are validated using numerical and theoretical data available in the literature. The analysis is accomplished for spherical shells of different geometries, boundary conditions and radius to thickness ratios. This proposed hybrid finite element method can be used efficiently for design and analysis of spherical shells employed in high speed aircraft structures.

The Finite Element Analysis of Dynamic Interaction of High-Speed Shinkansen, the Rail, and Bridge

1993 ◽  
Author(s):  
Makoto Tanabe ◽  
Hajime Wakui ◽  
Nobuyuki Matsumoto
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
High Speed ◽  
Response Analysis ◽  
Element Formulation ◽  
Element Analysis ◽  
Finite Element Program ◽  
The Finite Element Analysis ◽  
Element Program ◽  
The Impact

Abstract A finite element formulation to solve the dynamic behavior of high-speed Shinkansen cars, rail, and bridge is given. A mechanical model to express the interaction between wheel and rail is described, in which the impact of the rail on the flange of wheel is also considered. The bridge is modeled by using various finite elements such as shell, beam, solid, spring, and mass. The equations of motions of bridge and Shinkansen cars are solved under the constitutive and constraint equations to express the interaction between rail and wheel. Numerical method based on a modal transformation to get the dynamic response effectively is discussed. A finite element program for the dynamic response analysis of Shinkansen cars, rail, and bridge at the high-speed running has been developed. Numerical examples are also demonstrated.

Parametric Modeling and Simulation of Taper-Lock Connection in Wind Turbine Spindle Based on ANSYS

2012 ◽  
Vol 622-623 ◽  
pp. 1140-1142
Author(s):  
Li Mei Wu ◽  
Yong Zhao Li ◽  
Yan Rong Wang ◽  
Fei Yang
Keyword(s):  
Finite Element ◽  
Wind Turbine ◽  
Structural Model ◽  
Theoretical Data ◽  
Limit Load ◽  
Parametric Modeling ◽  
Stress And Strain ◽  
Finite Element Software ◽  
Load Conditions ◽  
Planet Carrier

Taking taper-lock Connection in Wind Turbine Spindle as research object, the paper analyzes the relativity of structural sizes and builds the parametric structural model by means of a way APDL. By using the non-liner finite element software ANSYS, the stress of taper-lock on the limit load conditions is analyzed, then contact stress and strain of the planet carrier and spindle are discussed. This is useful to the choice of assembly condition during taper-lock, planet carrier and spindle and providing theoretical data.

Some Remarks on Spherical Shells

1965 ◽  
Vol 32 (1) ◽  
pp. 121-128
Author(s):  
C. N. DeSilva ◽  
H. Cohen
Keyword(s):  
Asymptotic Solution ◽  
Spherical Shell ◽  
Variable Thickness ◽  
Transverse Shear ◽  
Correction Term ◽  
Transverse Shear Deformation ◽  
Governing Equations ◽  
Spherical Shells ◽  
Annular Disk ◽  
Thickness Function

The present paper treats the deformation of a spherical shell within the framework of a linear bending theory which includes the effect of transverse-shear deformation. A two-term asymptotic solution of the governing equations is obtained which embraces all terms of an order retained in the formulation of the theory. The solution is valid within a physically important domain of the shell and reduces to the previously known one-term asymptotic solution of the classical bending theory. The problem of variable thickness is also discussed. The behavior of the thickness function may be such as to require in the solution a correction term which may contribute significantly to the deformation. This solution is applied to a treatment of the deformation of a rotating, completely closed spherical shell stiffened by an annular disk located normal to the axis of the spin.

Theoretical Performance of a Hydrostatic Foil Bearing

1994 ◽  
Vol 116 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Marc Carpino ◽  
Jih-Ping Peng
Keyword(s):  
Finite Element ◽  
Reynolds Equation ◽  
Structural Model ◽  
Three Dimensional ◽  
Element Model ◽  
Element Formulation ◽  
Foil Bearing ◽  
Dimensional Finite Element ◽  
Membrane Effects ◽  
Three Dimensional Finite Element

The performance of a hydrostatic foil journal bearing operating with an incompressible fluid is discussed. In the configuration considered here, pressurized lubricant fluid is supplied through capillaries to recessed pockets on the surface of the journal. The foil is treated as a perfectly flexible, inextensible shell by a three dimensional finite element model. The pressure distribution is predicted by a finite element formulation of the incompressible Reynolds equation. Results are presented which demonstrate that the foil structure enhances load support while increasing lubricant film thickness. In addition, results indicate that membrane effects are essential in the structural model.

On the Numerical Modeling of High-Speed Hydrodynamic Gas Bearings

1999 ◽  
Vol 122 (1) ◽  
pp. 124-130 ◽  
Author(s):  
Marco Tulio C. Faria ◽  
Luis San Andre´s
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Numerical Study ◽  
Load Capacity ◽  
Finite Difference Methods ◽  
Element Formulation ◽  
Gas Flows ◽  
Computationally Efficient ◽  
Artificial Diffusion ◽  
Finite Element Schemes

A numerical study of high-speed hydrodynamic gas bearing performance is presented using both finite element and finite difference methods. Efficient numerical procedures are developed to analyze diffusive-convective thin film gas flows in some simple geometries. A novel direct finite element formulation employing a new class of shape functions is specially devised to solve the Reynolds equation for compressible fluids. The formulation is as computationally efficient as the classical upwind finite element schemes without introducing artificial diffusion into the solution. Bearing load-capacity, static stiffness coefficients and frequency-dependent force coefficients are calculated for gas-lubricated plane and Rayleigh step slider bearings. [S0742-4787(00)01701-X]

Frequency Response of a Three-Node Finite Element for Thick and Thin Plates

2002 ◽  
Vol 8 (8) ◽  
pp. 1123-1153 ◽  
Author(s):  
Humayun R. H. Kabir ◽  
Abdullateef M. Al-Khaleefi
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Correction Term ◽  
Thin Plates ◽  
Mode Shapes ◽  
Integration Scheme ◽  
Element Formulation ◽  
Transverse Shear Strain ◽  
Shear Locking ◽  
Triangular Finite Element

A shear-locking free isoparametric three-node triangular finite element is presented to study the frequency response of moderately thick and thin plates. Reissner/Mindlin theory that incorporates shear deformation effects is included into the element formulation. A shear correction term is introduced in transverse shear strain components to avoid the shear-locking phenomenon. The element is developed with a full integration scheme, hence, the element remains kinematically stable. Natural frequencies and mode shapes are obtained and compared with the available analytical and finite element solutions.

Elastic Stress Distribution in Layered Spherical Shells With Gaps Caused by Internal Pressure

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Shugen Xu ◽  
Chao Chen
Keyword(s):  
Finite Element ◽  
Spherical Shell ◽  
Elastic Stress ◽  
Outer Wall ◽  
Wall Surface ◽  
The Finite Element Method ◽  
Spherical Shells ◽  
Calculation Results ◽  
The Difference ◽  
Stress Discontinuity

An interlayer gap is inevitable in layered spherical shells. Therefore, the classic formulae for the monobloc spherical shell can no longer be used. In this paper, the formulae for the elastic stress calculation of layered spherical shells were proposed and the difference between the proposed formulae and ASME formulae was clarified. Interlayer gaps induce stress redistribution and stress discontinuity in the layered spherical shell. The hoop stress in the inner wall surface becomes higher than that in the monobloc spherical shell, and the stress in the outer wall surface is lower. Calculation results obtained from the proposed formulae were compared to those obtained by the finite element method (FEM) and ASME formulae. It was shown that the results from the proposed formulae are in accordance with finite element results.

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